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BACKGROUND: Near-infrared fluorescence imaging using intravenous indocyanine green (ICG) facilitates intraoperative identification of biliary anatomy. We hypothesize that a much lower dose of ICG than the standard decreases hepatic and background fluorescence and improves bile duct visualization. STUDY DESIGN: In this multicenter randomized controlled trial, 55 adult patients undergoing laparoscopic cholecystectomy were randomized to low-dose (0.05 mg) or standard-dose (2.5 mg) ICG preoperatively on the day of surgery. A quantitative assessment was performed on recorded videos from the operation using ImageJ software to quantify the fluorescence intensity of the bile duct, liver, and surrounding/background fat. Operating surgeons blinded to ICG dose provided a qualitative assessment of various aspects of the visualization of the extrahepatic biliary tree comparing near-infrared fluorescence to standard visible light imaging using a scale of 1 to 5 (1, unsatisfactory; 5, excellent). Quantitative and qualitative scores were compared between the groups to determine any significant differences between the doses. RESULTS: The bile duct–to–liver and bile duct–to–background fat fluorescence intensity ratios were significantly higher for the low-dose group compared with the standard-dose group (3.6 vs 0.68, p < 0.0001; and 7.5 vs 3.3, p < 0.0001, respectively). Low-dose ICG had a slightly higher (ie better) mean score on the qualitative assessment compared to the standard dose, although the differences were not statistically significant. CONCLUSIONS: Low-dose ICG leads to quantitative improvement of biliary visualization using near-infrared fluorescence imaging by minimizing liver fluorescence; this further facilitates routine use during hepatobiliary operations.

Introduction: Hypothermic machine perfusion (HMP) has greatly facilitated kidney allograft preservation. However, tissue damage still occurs during HMP, deleteriously affecting post-transplant graft function. Therefore, improved methods to assess organ quality and to predict post-transplant graft function and survival are needed. We propose that soluble DNA (sDNA) measured in HMP perfusate can used as a non-invasive biomarker for this purpose. Methods: Perfusate samples of kidney grafts placed on HMP were collected after 5 minutes and at the conclusion of HMP. sDNA of nuclear origin within the perfusate was quantified by real-time polymerase chain reaction and correlated with HMP parameters and post-transplant clinical outcomes. Results: Kidney grafts from 52 donors placed on HMP were studied. Perfusate sDNA concentration was significantly elevated in transplanted kidneys with delayed graft function. Grafts with higher concentrations of perfusate sDNA at 5min and at HMP conclusion also had reduced graft function in the initial post-transplant period, as measured by post-operative day 2, 3, and 4 creatinine reduction ratios (CRR). Standard pump parameters such as renal vascular resistance and renal vascular flow were poor indicators of early post-transplant graft function. Conclusion: sDNA concentration in HMP perfusate of kidney grafts can predict the quality of kidney graft preservation and indicate post-transplant renal function. This biomarker should be explored further to improve renal organ assessment and transplantation outcomes.